The Lac de Serre-Ponçon is surrounded by a setting of mountainous massifs with contrasting reliefs which owe their high altitude to the piling up of units carted on either side of the lake. The most imposing of them is certainly the Morgon massif. Located in the extension of the Pic de Morgon (photo), it forms an enormous block of limestone placed on a base of black earth and ends in the north with cliffs overhanging the lake.